Does anyone have recommended settings to use the old Speedlite 200e flash (I have had this for almost 18 years and still works well for its limited functionality) with the 40D? I just want to hold off on a purchase of a new flash for a little while for obvious economic reasons.

I have tried using several settings - manual, Av and Tv, the manual mode worked best for me with various settings on trial and error basis.

You won't get any sort of automatic operation, so using it in fully manual exposure mode and setting aperture based on the guide number and ISO setting is the way to go.

The GN is 66 (ft) for ISO 100.

To get the aperture you divide the GN by the distance, so at 16ft, the aperture would need to be around f4 at ISO 100.

The GN at iso 400 would be 122 and at 1600 it would be 244. So at iso 400, a subject at 16ft from the camera should be properly exposed by the flash if the aperture is set to f8

The shutter speed should be 1/200s or faster, depending on what you need to give you the background that you want. The flash illumination is so fast that shutter speed doesn't affect the exposure for the flash, only for the ambient light.